383 won't start. It cranks, I have spark & fuel - could it be the battery

I don't know about BC gas, but here in Manitoba, oxygenated gas will not start well after 1 week stored in a vented container, IN SUMMER, never mind at temperatures at or below freezing.
Your fuel tank is vented, and depending on where you are in BC, temperature swings can be frequent.Temperature swings can drive a vented tank into "breathing".
So unless your fuel was fresh and stabilized when you parked it,and if your garage is un-heated, the temperature swings,and time, can be driving all the lighter, more volatile components into the atmosphere, and the fuel may be sucking up moisture out of the atmosphere, and the fuel may be turning into syrup.
So the first thing I would do is drain some of that gas into a clear glass jar.If the gas is clear to very light yellow,it's ok. If it is dark yellow, it is past it's best-before date but may power up your lawnmower. If it orange to reddish it is not even good for making fire-starter,and I would get rid of it.
Either your battery did not receive a proper re-charge, or the fluid level in it is very low, or there is/are very high-resistance connections in the circuit somewhere or it is toast. Depending on the rate of charge that you were using, and the temperature of the environment in which the battery sits, it can take up to a week or more to bring her back to life.You really need a battery tender to overwinter a lead-acid battery.I have seen some batteries require a month of charging on a trickle charger,at 1.5 to 2.0 amps, before they recovered.